commit adcc6d3139f5731ba8e2272e4e3c24605768c955
Author: Rushikesh <rushikeshnalla9@gmail.com>
Date:   Thu Jan 14 21:16:11 2016 +0530

    MDL-33663 Grading methods: Appropriate error message for negative grades

diff --git a/grade/grading/form/guide/lang/en/gradingform_guide.php b/grade/grading/form/guide/lang/en/gradingform_guide.php
index 87f7a11..38e9ca7 100644
--- a/grade/grading/form/guide/lang/en/gradingform_guide.php
+++ b/grade/grading/form/guide/lang/en/gradingform_guide.php
@@ -58,6 +58,7 @@ $string['err_nomaxscore'] = 'Criterion max score can not be empty';
 $string['err_noshortname'] = 'Criterion name can not be empty';
 $string['err_shortnametoolong'] = 'Criterion name must be less than 256 characters';
 $string['err_scoreinvalid'] = 'The score given to {$a->criterianame} is not valid, the max score is: {$a->maxscore}';
+$string['err_scoreisnegative'] = 'The grade is invalid as it is negative and acceptable range is 0 - {$a->maxscore}';
 $string['gradingof'] = '{$a} grading';
 $string['guide'] = 'Marking guide';
 $string['guidemappingexplained'] = 'WARNING: Your marking guide has a maximum grade of <b>{$a->maxscore} points</b> but the maximum grade set in your activity is {$a->modulegrade}  The maximum score set in your marking guide will be scaled to the maximum grade in the module.<br />
diff --git a/grade/grading/form/guide/lib.php b/grade/grading/form/guide/lib.php
index a6c17eb..25c797e 100644
--- a/grade/grading/form/guide/lib.php
+++ b/grade/grading/form/guide/lib.php
@@ -795,7 +795,7 @@ class gradingform_guide_instance extends gradingform_instance {
                     || $criterion['maxscore'] < $elementvalue['criteria'][$id]['score']
                     || !is_numeric($elementvalue['criteria'][$id]['score'])
                     || $elementvalue['criteria'][$id]['score'] < 0) {
-                $this->validationerrors[$id]['score'] =  $elementvalue['criteria'][$id]['score'];
+                $this->validationerrors[$id]['score'] = $elementvalue['criteria'][$id]['score'];
             }
         }
         if (!empty($this->validationerrors)) {
@@ -943,8 +943,13 @@ class gradingform_guide_instance extends gradingform_instance {
                     $a = new stdClass();
                     $a->criterianame = s($criteria[$id]['shortname']);
                     $a->maxscore = $criteria[$id]['maxscore'];
-                    $html .= html_writer::tag('div', get_string('err_scoreinvalid', 'gradingform_guide', $a),
+                    if ($this->validationerrors[$id]['score'] < 0) {
+                        $html .= html_writer::tag('div', get_string('err_scoreisnegative', 'gradingform_guide', $a),
                         array('class' => 'gradingform_guide-error'));
+                    } else {
+                        $html .= html_writer::tag('div', get_string('err_scoreinvalid', 'gradingform_guide', $a),
+                        array('class' => 'gradingform_guide-error'));
+                    }
                 }
             }
         }